Space spraying relies on a large number of small insecticidal droplets distributed through a volume of air over a given period of time. A lethal dose of insecticide targets insects upon impact. There are two traditional methods of space spray:
- Thermal Fogging – a dense cloud of insecticide droplets give the appearance of a thick fog
- Ultra Low Volume (ULV) – droplets are generated by a cold, mechanical, aerosol-generating machine
Space spraying is a very effective way to rapidly reduce the population of flying insects in a specific area. The method must be repeated at 5-to-7 days intervals in order to be effective because there is no insecticide residual activity. This method can be particularly effective where rapid reduction in mosquito numbers is required, such as during an epidemic. As such, it is very helpful in controlling mosquitoes carrying dengue and Zika in urban areas.
Effective space spraying is dependent upon the optimal droplet size. When droplet size is optimal target insects fly through the spray and are affected. They can also be affected while resting on exposed surfaces. The droplet size must be optimized so that spray droplets remain airborne for the optimum period of time and that they contain the right dose of insecticide. The optimum size of droplets for space-spray application are droplets with a Volume Median Diameter (VMD) of 10–25 microns.
Droplets too large or too small are ineffective. If droplets are too big, they drop to the ground too quickly and limit the area of application. Also, if a large droplet impacts an individual insect, it can be “overkill” since a high dose will be delivered to that particular insect. If droplets are too small then they may either not deposit on a target insect (no impact) due to aerodynamics or they can be carried upwards into the atmosphere by convection currents.
Bayer pioneered the development of anti-evaporant technology by introducing the innovative spray technology called FFAST (Film Forming Aqueous Spray Technology) which reduced the need for use of hydrocarbon solvents in space spray application. FFAST formulations are primarily water-based, are diluted with water and achieve optimal efficacy. These formulations have been proven effective in many situations around the world. This technology is available in Aqua K-Othrine and Aqua Reslin Super.